Visual display method and apparatus

ABSTRACT

Apparatus for generating a realistic wide-screen visual display for an aircraft simulator with realistic perspective throughout plural widely different phases of simulated flight by scanning a plurality of different successive types of transparencies with a flying spot scanner to derive video signals to drive television display projectors, including the scanning of a pair of transparencies to provide a background terrain elevation image without topographical features, scanning of a second type of transparency to provide an image of an airport or the like to be inset into the background image and distorting the inset image as simulated range and elevation angle from the airport vary, scanning a third type of transparency to provide a different type of inset image during simulated approach and landing and distorting that inset image in accordance with deviation of the simulated aircraft from a reference glideslope, and scanning a fourth type of transparency to provide a panoramic view of the airport during simulated taxiing and parking maneuvers, with means for automatically controlling the successive scanning modes with signals from a flight computer.

United States Patent {72] Inventor William C. Ebeling FOREIGN PATENTS B g 751,628 7/1956 Great Britain... 35/12 PP 735,109 896,404 5/1962 Great Britain... 35/12 d 3 :533 1,037,060 7/1966 Great Britain 35/12 a en e ay [73] Assignee Singer-General Precision, Inc. f' f Momson Assistant Exammer-Fehx D. Gruber Bingharnton,N.Y.

Attorneys-Francs L. Masselle, W1l11am Grobman and Andrew G. Pullos [S4] VISUAL DISPLAY METHOD AND APPARATUS 46Cl 26D F aims ABSTRACT: Apparatus for generating a realistic wide-screen U-S- visual for an aircraft imulator realistic perspec- 35/12N, 35/123, 353/11, 353/30 tive throughout plural widely difi'erent phases of simulated Int. canning a plurality of different successive types of 8 7/72 transparencies with a flying spot scanner to derive video {50] Field of Search 35/ 10.2, Signals to drive television dismay pmjecmrs, including the 12 N; 178/6-8 scanning of a pair of transparencies to provide a background [56] References cited terram elevat1on lmage w1thout topographical features, scannlng of a second type of transparency to prov1de an lmage UNITED STATES PATENTS of an airport or the like to be inset into the background image 2,883,763 4/ 1959 Schaper 35/12 and distorting the inset image as simulated range and elevation 2,999,322 9/1961 l-lemstreet... 35/12 angle from the airport vary, scanning a third type of trans- 3,076,271 2/1963 Marvin et al. 35/12 parency to provide a different type of inset image during simu- J L 8/1963 Hemstreetm 35/12X lated approach and landing and distorting that inset image in 3,233,508 2/ 1966 Hemstreet... 35/ 12X accordance with deviation of the simulated aircraft from a 3,261,912 7/1966 Hemstreet 35/ 12X reference glideslope, and scanning a fourth type of trans- 3,284,923 11/1966 Leslie 35/8 parency to provide a panoramic view of the airport during 3,367,046 2/1968 Neuberger 35/12 simulated taxiing and parking maneuvers, with means for au- 3,439,l05 4/1969 Ebeling et a1... 35/ 10.2 tomatically controlling the successive scanning modes with 3,451,144 6/ 1969 Chao et a1 35/10.2 signals from a flight computer.

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Patented May 25, 1971 3,580,978

12 Sheets-Sheet 1 sgA LEvEg FIG. 2b

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TERMINAL BUILDING I WILLIAM C. EBELING Fl G. 2c INVENTOR HIS AITORNEY Patented May 25, 1971 COMPUTER o.- 99

a MULITIPLIER 12 Sheets-Sheet 6 ERROR COMPUTER FIGJO I18 I20 I44 X. TOFILM I HORIZONTAL I DEFLECTION I time AMPLIFIER l m? VERTICAL MASK DEFLECTION 2 42 AMPLIFIER PHOTOMULTIPLIER "2 28 I50 WILLIAM C. EBELING 'INVENTOR BY My; HIS ATTORNEY Patented May 25, 1971 12 Sheets-Sheet 7 mNN KMPDQEOO 101mm ZOEwOa IP54.

mummy-m;- PEEIUm WILLIAM C. EBELING INVENTOR BY 4: A 5

HIS ATTORNEY Patented May 25, 1971 v- 3,580,978

12 Sheets-Sheet 9 INSET LINE WIDTH COMPUTER arm-i- TO F GJG I I I H I l HEADING SUMMER LINE COUNTER WILLIAM c. EBELING Fl (5 l3 INVENTOR (Zia M HIS ATTORNEY VISUAL DISPLAY METHOD AND APPARATUS This invention relates to visual display method and apparatus, and, more particularly, to novel method and apparatus for providing simulated displays which realistically depict scenes as they would be viewed from traveling vehicles, such as aircraft. The invention is particularly useful for the simulation of takeoff, landing and ground-maneuvering of aircraft in connection with training or amusement apparatus.

One prior art visual display system for simulating movement of the observer involves the use of a transparent three-dimensional model of an airport and a point light source, and is typified by DeFlorez et al. U.S. Pat. No. 2,96l ,778. Such systems are disadvantageous in that such models are extreme-. ly expensive to construct, so that simulation is ordinarily limited to flight over very confined areas, and in that it is difficult to provide adequate brightness in point light source systems. Also, such systems are unrealistic in that objects depicted in such systems appear to become more blurred as they are approached, a phenomenon usually quite opposite to that of the real world.

A second type of prior art visual display system involves the use of a television camera flown" with 6 of freedom with respect to a three-dimensional airport model, as typified by U.S. Pat. Nos. 3,012,337 and 2,979,832. Such systems either have used extremely large, bulky and expensive models, or if a small modelhas been used, they have sufiered from focusing problems, due in general to the fact that the viewing lens cannot be reduced in size proportionally. Also, when a large scale factor is used to enable the size of the model to be reduced, vibration of the television cameraor its lens system relative to the model results in greatly magnified and unrealistic jerks and jumps in the final visual display provided to the observer.

A third type-of prior art visual display system employs flying spot scanner means and two flat transparencies representing the relevant terrain. By controlling the flying spot scanner sweep on one transparency in accordance with simulated motion of the observer, video signals of proper luminance (and color, if desired) to display the relevant terrain are provided.

By simultaneously and synchronously sensing elevation data which is density-coded on the second transparency, further signals may be derived and used to process the luminance video signals to provide a final cathode-ray tube presentation having a perspectively corrected scene. Various systems of this type are shown in my copending joint application with Eldred H. Paufve, Ser. No. 442,392, filed Mar. 24, l965, now U.S. Pat. No. 3,439,105. While systems of this type provide realistic three-dimensional displays of natural terrain, they have been unable to provide similar realism for cultural (manmade) objects, so, for example, a display provided with such a system may realistically show hills and valleys, but the terrain always looks bare, and devoid of buildings or roads or the like. The absence of cultural features is not serious when flight at fairly great altitudes is simulated, but the lack of cultural features renders such displays unsuitably unrealistic for many training applications. The system shown in the above-mentioned copending application also suffers from focusing problems when it is used to depict scenes, such as those needed to simulate landings of an aircraft, when both near and far objects would be visible, so that an extreme depth of focus is required from the system. A primary object of the present invention is to provide a visual display which realistically depicts not only natural terrain, but also cultural objects, with realistic perspective.

A further type of prior art visual display apparatus is marketed under the trademark "VAMP" by General Precision Systems lnc., and is illustrated in a number of patents issued to Harold S. Hemstreet, including U.S. Pat. Nos. 2,999,322 and 2,975,671, for example. Various of the Hemstreet patents dis close the idea of providing a motion picture filmstrip of a scene as it would appear in normal flight along a reference path, and of projecting the film as a flight simulator flies along an approximation of that path, and simultaneously distorting" or reshaping the projected picture in accordance with the displacement between the viewpoint from which each frame was taken along the reference path and the simulated position along the simulated flight path at the instant when a given frame is projected. While such systems are extremely realistic for some flight patterns, and generally quite satisfactory for simulation of very many approaches, landings, and takeoffs, they become unrealistic if a given simulated path departs too much from the reference path along which the film was taken, so that an extreme amount of distortion has to be applied to the projected images. Under such conditions, the actual vertical edges of three-dimensional objects such as trees and houses in the projected scene noticeably appear to lean away from the vertical.

A more serious objection to the use of the VAM P" systems for some training purposes, is the fact that the path of travel is substantially preprogrammed, or fixedly predetermined. The Hemstreet systems, in allowing flight path variations over a range of several degrees, were, so far as I know, the first visual display systems using motion picture films as the basic storage medium which did not need to be completely preprogrammed. However, it is highly advantageous in many training applications that the display be even much less programmed, so that realistic simulation can be provided, not only throughout the envelope of a standard [LS system, but over a much wider area. The prior invention of the mentioned Ebeling-Paufve application has the advantage over the Hemstreet system that simulated flight, though it must be at high simulated altitudes, may be completely unprogrammed over an area of many square miles and still be quite realistic, although the Hemstreet systems are much preferred for landing and takeoff simulation.

The present invention borrows several features of the Hemstreet systems, several features of the Ebeling-Paufve system shown in the copending application, and combines them with a number of new features to provide a realistic display which is usable over practically all flight regimes, from taxiing out to a runway, through takeoff, flight at both high and low altitudes, approach, landing and taxiing up to an unloading ramp. ln accordance with the present invention, the basic Ebeling-Paufve system is used at altitudes above a selected level, so that jet flights along any route to any place may be simulated, and an auxiliary system is used to inset features to provide more detail in portions of the display when simulated altitude decreases to a point where cultural objects should be noticeable. The basic Ebeling-Paufve system includes a cathode-ray tube in its output display system, and hence the function of the auxiliary equipment is to provide video signals representing the picture content to be inset, in order that such video signals may be switched to the cathode-ray tube display system at appropriate times. The substitute video signal used in the present invention may be derived from scanning film frame transparencies which represent scenes viewed along a reference path (or from points on a related group of reference paths), with the signals distorted in accordance with Hemstreets teachings, to account for the difference between the location of the simulated viewpoint of the student pilot at the instant when a given film frame is projected" (i.e. scanned and used to provide the video signals for the picture inset), and the location at which the camera was situated during the instant when the given film frame was taken.

As mentioned above, one problem which has discouraged more widespread use of the Hemstreet systems has been the fact that distortion has had to be limited to only a few degrees to avoid an unrealistic leaning of trees and buildings and the like. The idea of providing many film strips taken at many different approach angles, and of automatically selecting from among them in accordance with instantaneous simulated pilot-viewpoint location, so that much less distortion need be applied to any one filmstrip to allow simulated approaches from a given range of angles, has not been deemed suitable for use with the Hemstreet systems, as it apparently would require either a large number of synchronized projectors for a number of filmstrips or an extremely expensive and perhaps impossible mechanical means for very rapidly substituting frames from a number of different filmstrips into a single or a few projectors. If motion picture film is projected with a substantially conventional projector, in the manner suggested by Hemstreet, it is either extremely difficult mechanically or extremely expensive to provide a film feed device which can substitute frames from different strips with sufficient rapidity to avoid disconcerting flicker as the simulated approach angles vary. In the present invention, however, because film frames are scanned by a flying spot scanner, the electron beam of which can be indexed extremely rapidly and easily, it becomes practical to select at various instants between pictures representing a large plurality of reference paths covering different approach angles, so that viewpoint displacement over a wide area can be accommodated in large measure by filmstrip selection, and only a small residual viewpoint displacement error need be removed by distortion of the images of the selected film pictures. Thus, it is another object of the invention to provide improved visual display method and apparatus in which picture infonnation is provided by selection of pictures from various sequences of frames (filmstrips) showing the same area as viewed from different positions. It is a further object of the invention to provide such a visual display in which the picture information from those frames selected from various frame sequences is also distorted in order to simulate viewpoint displacement.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangement of parts which are adaptedto effect such steps, all as exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of an aircraft flight simulator incorporating one form of the invention;

FIG. 2 is a block diagram ofthe overall visual display apparatus included with the simulator of FIG. 1;

FIG. 2a is a geometric plan-view map of an airport useful in explaining the operation of the invention during simulation of flight at considerable distances from the airport;

FIG. 2b is an elevation diagram of FIG. 2a;

FIG. 2c is a plan view of an airport runway and terminal building useful in describing operation of the invention to simulate travel of an aircraft near a simulated airport terminal;

FIG. 3 illustrates one frame of 70 mm. film provided with a matrix of 50 pictures of a simulated airport and surrounding terrain, of which all 50 were taken facing toward the airport from positions located in the same azimuthal direction and at the same distance from the airport, but at 50 different elevation angles;

FIG. 4 is a diagram illustrating one frame of 70 mm. film provided with a matrix of 25 pictures of the airport all taken from the same distance from the runway touchdown point, with the central pictures taken down the center of the ILS glideslope, and with the surrounding pictures taken at slightly varying azimuths and'elevations from the glideslope. FIG. 4a is a graph illustrating the amount by which the pictures in a film frame such as that of FIG. 4 are distorted as the simulated aircraft deviates laterally from the centerline of the simulated glideslope;

FIG. 5 is a diagrammatic view of a glideslope and runway showing a plurality of photograph matrices of the type illustrated in FIG. 4 spaced relative to the glideslope and along the runway to indicate the viewpoints from which the various photographs of such photomatrices are taken;

FIG. 6 is a diagram illustrating how a plurality of filmstrips comprised of frames or photograph matrices, including the types shown in FIGS. 3 and 4, may be spliced together to allow continuous visual simulation throughout a plurality of different operating modes;

FIG. 7 is a block diagram of the flying spot scanner sweep control system of the airport image generator, together with certain portions of the overall visual display apparatus illustrated in FIG. 2;

FIG. 8 is a block diagram of the feedback raster centering system utilized with the flying spot scanner of the airport image generator to insure proper registration of the scanner raster with the photographs which it scans, together with certain details of the flying spot scanner sweep control system of FIG. 7;

FIG. 9 is a diagrammatic view of a centering mask used with the raster centering system ofFIG. 8;

FIGS. 9a, 9b and 9c illustrate portions of the centering mask which are used during different phases of a mission;

FIG. 10 is a block diagram of the raster position error computer portion of the raster centering system illustrated in FIG.

FIG. 11 is a diagram illustrating a general airport image inset at various locations into the background display which is useful in explaining operation of the switching logic circuit illustrated in FIGS. 7, l3 and 15;

FIG. 12 is a schematic diagram of the control system illustrated in block diagram form in FIG. 2, which automatically switch as the operation of the airport image generator through successive phases of the mission and which provides certain computed quantities to control the flying spot scanner of the airport image generator;

FIG. 13 illustrates portions of the switching logic circuit illustrated in FIG. 7;

FIGS. 13a, 13b and are geometric diagrams useful in explaining the operation of the switching logic system of FIG. 13;

FIG. 14 is a simplified schematic diagram of one form of the raster distortion computer illustrated in FIG. 7;

FIG. 15 is a schematic diagram of a portion of the switching logic circuit illustrated in FIG. 7 and the video combining and switching system illustrated in FIG. 2 in which video signals from the airport image generator may be combined with those from a background image generator to control the intensity grids of the television projectors; and

FIG. 16 is a schematic diagram of the raster position computer illustrated in FIG. 7 which positions the origin of the image generator flying spot scanner relative to the photograph which it scans.

Like reference numerals throughout the various views of the drawings are intended to designate the same or similar structures.

In an aircraft simulator installation shown in FIG. 1 incorporating a preferred embodiment of the invention, a student pilot and student copilot seated within simulator flight deck or cockpit 4 view the display on rear-projection screen S through a windscreen 11 of the cockpit and through a virtual image viewing system indicated generally at 12, which includes an ellipsoidal mirror 14 and an objective lens 16. The particular virtual image system is not an essential feature of the present invention, and various other known infinity-image viewing systems may be substituted. The scene provided on rear-projection screen S is provided by three television projectors l, 2 and 3, each of which covers a 60 horizontal sector of screen S, which is preferably in width. As shown in FIG. 1, screen S and projectors l3 are also preferably carried on cockpit 4, to pitch and roll with the cockpit. With screen S fixed relative to the cockpit windows 11, it will be appreciated that changes must be made in the projected display to simulate changes in aircraft heading, pitch angle and bank angle.

As indicated by the general system diagram of FIG. 2, the overall image provided by projectors l, 2 and 3 is composed, in video combining and insetting apparatus 5, from video signals from (I) a background image generator 7, which may be of the type described in the mentioned Ebeling-Paufve application, (2) an airport lighting image generator 6, if desired, of the general type shown in US. Pat. No. 3,081,557 issued to John Mailhot, and (3) the television and film airport display image generator 8 constructed in accordance with the principles of the present invention. Each of the three image generators is connected to be controlled by a plurality of input signals from a simulator flight and navigation computer 17, in accordance with the attitude and position of the simulated aircraft with respect to various reference points and reference directions, and in accordance with simulated weather or visibility conditions. The present invention may be used with conventional simulator flight computers of either the digital or the analog type or various hybrid digital/analog types. Computing apparatus for performing the function of the computer 17 are disclosed in US. Pat. No. 2,925,667 and US. Pat. No. 3,233,508.

A pulse source 19 provides sync pulses to a plurality of vertical and horizontal projector sweep generators and to the sweep generators (not shown) in the image generators 6 and 7. Outputs of the projector sweep generators 20 are supplied to respective ones of the projectors 1, 2 and 3 and also to the image generators 6 and 7. In addition, outputs of the projector sweep generators 20. are supplied to a sweep control system 18 which supplies horizontal and vertical sweep signals to a flying spot scanner (FSS) 21 which forms a part of the airport image generator 8. In order to properly inset images from the airport image generator 8 onto background images generated by the image generator 7, the sweep control system 18 provides control signals to the video combining and switching system 5 on a line 22. A transparency 23 which contains an image of the airport is controlled positionaly by a film drive servo M-20l which is driven in accordance with signals derived from the flight computer and control system 17. The FSS 21 scans the transparency 23 and video signals are generated by photomultiplier 24 and transmitted through video processing circuits 25 to the video combining and switching system 5.

The flight computer and control system 17 is preconditioned with certain airport position characteristics from an instructor and is responsive to signals from a simulator which are indicative of the apparent position of the simulator and provides outputs in accordance therewith to the image generators 6 and 7, the sweep control system 18 and the film servo drive M-20l. In addition, a simulated change in bank angle of the simulator controls the projector sweep generators 20 and the projectors 1, 2 and 3 by means of the mechanical linkage designated 0.

The preferred embodiment of the invention contemplates that simulated flight at simulated high altitudes and a predetermined distances (e.g. 4 miles or more from the airport to be simulated) will provide on screen S solely a background display without cultural features, of the type described in application Ser. No. 442,392, by means of the known form'of background image generator 7. When the simulator simulates an actual aircraft approaching to within a distance of perhaps 4 miles from the airport, a general airport image showing the airport and some surrounding terrain will be derived by airport display image generator 8 of the present invention and inset into the background display. When first inset into the background display, the general airport image will occupy a very small portion of screen S and barely be visible, but as the simulator simulating an actual aircraft flying nearer to the airport, the general airport image will occupy an increasingly greater portion of screen S. As simulated aircraft attitude varies, the position on screen S of the inset video must vary, so that at various times the inset video will be displayed by any one of the three projectors, and indeed sometimes different portions of it will be projected onto screen S by two different ones of the three projectors. During this phase of flight simulation, which will be referred to as the general airport image" phase, the general airport image display is produced by scanning one of-a large number (e.g. 180,000) of pictures of the airport and surrounding terrain all taken at the same range from the airport but at different azimuths and elevations from the airport. For example, the pictures may be taken one at every 6 minutes of azimuth (i.e., from 3,600 different azimuth positions around the airport) for each of 50 different elevation increments, all at a range of several miles from the airport, to

provide a total of 180,000 pictures. The 50 different pictures all taken at a given azimuthal position preferably are mounted together in a matrix (rows and columns) to form one frame" of the strip 23 of 70 mm. film, one exemplary frame of such a filmstrip being shown in FIG. 3. As the simulator simulates an actual aircraft flying nearer to the airport, the size of the scanning raster on one of the 180,000 pictures being scanned at the time is decreased to increase the size of the airport image being inset into the background display, and as the simulator simulates an actual aircraft successively reaching different azimuthal and elevation angles relative to the airport, appropriate different ones of the 180,000 pictures are automatically and successively selected and scanned to provide the video signals which are inset into the background display. If 50 pictures taken at a given azimuth are included in each frame of a 70 mm. film, a film strip of approximately 830 feet is required for the l80,000 pictures.

As the simulator simulates an actual aircraft circling around the airport, the film drive servo M-201, controlled in accordance with the instantaneous bearing of the simulated aircraft from the airport, successively positions appropriate frames of the strip 23 in front of the scanning device 21. If the simulator simulates an actual aircraft approaching the airport at a fixed azimuth and at a fixed elevation angle, a single one of the pictures is increasingly blown up in the projected display. Whenever a given one of the pictures is scanned, if the simulator simulates an actual aircraft which varies in elevation from the point where the picture was taken, the FSS scanning raster is distorted to provide proper perspective in the scene inset into the background display. If the simulator simulates an actual aircraft which approaches at a fixed azimuth but at successively varying elevation angles relative to the airport, various of the 50 pictures on the single frame corresponding to that azimuth are successively scanned. In FIG. 3 each of the 50 rectangles representing a different picture is shown labeled with the particular elevation-angle from which it was taken. It may be noted that the 50 pictures are arranged with increasing elevations running back and forth across the frame in successive rows, so that a change from scanning one photograph to scan another photograph associated with the next higher or next lower elevation angle simplifies control of and requires minimum indexing of the flying spot scanner 21 by the sweep control system 18.

When the simulator simulates an actual aircraft which reaches a predetermined approach position within a predetermined distance from the airport and within a predetermined approach window," which may comprise, for example, the azimuth and altitude positions in which ILS signals may be received, and while the simulator simulating an actual aircraft which flies down the [LS beam, touches down, and rolls along the main runway, the video signals derived by image generator 8 and inset into the background display are derived by scanning one picture at a time of a different type of film mosaic or matrix of the type illustrated in FIG. 4 wherein the 25 pictures comprising a given film frame again were all taken at the same distance from a reference touchdown point and facing toward the touchdown point, but at slightly varying azimuths as well as elevations from the reference touchdown point. During this phase of simulation individual pictures on successive frames of the type shown in FIG. 4 are scanned, with successive frames carrying pictures taken successively nearer the touchdown point, and as the simulated path of the aircraft being simulated varies above and below the glideslope or departs in azimuth from the center of the glideslope, appropriate different pictures are selected and scanned to produce the video to be inset into the background. When a given one of the pictures is scanned, if the simulator simulates an actual aircraft which varies in elevation or azimuth (or both) from the point where the picture was taken, the FSS scanning raster is distorted to provide proper perspective in the scene inset into the background display. After the simulator has simulated an actual aircraft which has touched down, or, more precisely, has proceeded a sufficient distance along the runway and is at a low enough altitude for an assumption to be made that touchdown has occurred, further simulation of changes in elevation need not be provided, and hence from a point T (FIG. 2c) where touchdown may be assumed to have occurred, all of the pictures on matrices corresponding to that of FIG. 4 may be used for photographs taken at the same height at different lateral positions across the runway. This phase, during both approach down the glide path and roll along the main runway will be referred to as the approach" phase for convenience. During this phase, because the runway picture may be assumed to be within the 60 forward view of the crew in the absence of a gross piloting error, and because crew attention should be focused on the runway, the video signal developed by airport image generator 8 is all inset into the central portion of screen S by projector 2, and projectors I and 3 merely provide a blurred background. To better understand this phase, reference may be had to FIG. wherein a glideslope line XT is shown projecting upwardly (at 2) from an airport runway 10, with glideslope XT intersecting runway 10 at touchdown point T. Shown spaced along line X- T and along runway 10 are a plurality of mosaics (M,, M,, ....M,,, and T,, T,, etc.) of motion picture film frames of the type shown in FIG. 4. Each mosaic or matrix is shown as comprising a group of 25 pictures (transparencies), with the center picture in each mosaic depicted as having been taken from a vantage point located precisely on glideslope XT (for the M" pictures taken prior to touchdown), or from a vantage point along a horizontal reference line XX' for those pictures taken after touchdown. Three successive pictures from vantage points located precisely on glideslope X- T comprise the three central pictures X,, X and X of mosaics M,, M and M respectively. Pictures X,, X, and X may comprise three successive frames of a motion picture sequence taken as' an actual aircraft descends along an actual glidepath, or alternatively may comprise three pictures taken as a camera is maneuvered relative to a scale model.

In addition to the central views taken along the glideslope XT, each M mosaic is shown as including 24 further pictures taken atthe same respective distances from touchdown point T, but taken from positions spaced at slight angles from reference glideslope XT. For example, pictures taken at positions along a line displaced 45 are minutes to the (pilot's) left from line XX are labeled L,,, L L,,, in FIG. 5, while pictures taken a further 45 are minutes, or a total of 1.5 to the left from line XX are labeled L L L Similarly, pictures R,, and R in mosaic M, of FIG. 4 are pictures taken 45 minutes and 1.5, respectively, to the right of line XX. Pictures marked U,, and U,,, are taken are minutes and 30 are minutes, respectively, up from or above glideslope XT, while pictures labeled D,, and D are taken from similar positions below line XT. Thus, each mosaic or matrix of 25 pictures includes those taken within an area which varies plus or minus are minutes (0.5) in altitude from reference line X- T, arid which varies plus or minus l.5 laterally from glideslope X--T.

If the 25 pictures of the matrix M, shown in FIG. 4 are assumed, for example, to have been taken 1000 feet out from point T in FIG. 5, with glideslope XT projecting upwardly at 2.0" in a northerly (0 azimuth) direction, central photograph X, in such a case would have been taken on line XT from an altitude of 1000 sin 2 or 34.9 feet. Photograph L,,, which is displaced 45 are minutes to the left would have been taken at the same altitude but from a position (sin 45 are minutes times 1000 feet) or approximately 13.1 feet east of where photo X, was taken. During the approach phase a filmstrip comprising the successive mosaics M,, M,, M,,, T,, T,, etc., is fed to a flying spot scanner at a film speed corresponding to the progress of the simulated aircraft along the simulated glidepath and simulated runway. If the simulator simulates an actual aircraft progressing exactly along glideslope XT, or more precisely, so that the pilots eye would travel along line XT, with no deviation whatever from the XT path, only the central X pictures X,, X,, X,,....X,, would be successively scanned by the scanner and used for the display projected to the students. If,

' instead, the simulator simulates an actual aircraft approaching on a steeper glideslope exactly l5 arc minutes higher than reference glideslope XT, only the U pictures U,,, U,,, etc. of the mosaics would be scanned by the scanner. In either case, successive mosaics or matrices are presented to the scanner at a rate proportional to the velocity component of an actual aircraft being simulated along path X-T. However, in typical flight, the actual aircraft will wander at various times either above or below, or to the right or left of reference path XT.

In the invention, as the simulator simulates an actual aircraft which moves within the glideslope envelope covered by the mosaics of the aircraft being simulated within the envelope determines at each instant both which single picture ofa given mosaic will be scanned and the nature of the scanning pattern used by the flying spot scanner. For example, as the simulator simulates an actual aircraft which translates to the left within the envelope, the scanner scans the central X pictures with increasing distortion as the simulator simulates an actual aircraft which moves from the centerline of the glideslope XT out 22.5 are minutes to the left, but then indexes and begins to scan L,,, L or L pictures with an opposite type of distortion. As the simulator simulates an actual aircraft which proceeds further to the left, the L,,, L or L picture is scanned with decreasing distortion, to where no scanning raster distortion is employed when the simulated aircraft is 45 are minutes to the left. The same procedure then would be repeated for further simulated motion to the left and indexing to scan L L or L pictures. Similar procedures govern simulated translation to the right, or up or down, and combinations of such deviations from glideslope XT, or from runway reference line X'X. A plot of the amount and direction of lateral distortion against angular deviation #1,, on either side of the centerline of the glidepath is shown in FIG. 4a together with indications of which frame of mosaic M, is scanned for a given lateral deviation. A plot for vertical deviation would be identical except for the angular values given.

When the simulator simulates an actual aircraft which reaches a reference point on the main runway, turns from the main runway and proceeds along a service runway, and taxis up to a ramp or gate and stops, the visual display is produced using a third mode of operation which involves scanning successively portions of appropriate ones of a plurality of panoramic pictures which illustrate views as seen from an actual aircraft on the ground, including buildings and the like, and successive panoramic pictures of such a plurality taken at a variety of distances from the airport gate are successively scanned. During this phase, which may be termed the taxi phase, the video signals derived from scanning a panoramic picture preferably are applied appropriately to all three projectors to entirely cover screen S. Each film frame used during the taxi phase may comprise a frame similar to that shown in FIG. 4 except that each of the five rows comprises a single panoramic picture, with each picture taken at the same distance from a reference point, such as a gate or ramp, associated with the airport but at a different lateral position on the service runway.

While airport image display generator 8 could use separate flying spot scanners for the several mentioned phases of simulation, it is possible and economically desirable to use the same scanner system for all the films required during an entire mission, by imposing only minor constraints on the flexibility of the system. The films must be arranged, however, for smooth transition from one matrix format to the next, and it is desirable to arrange the filmstrips so that the first matrix to be used in one phase of the mission is adjacent the last frame used in the previous phase of the mission. FIG. 6 illustrates one manner in which successive film sections may be spliced together for such purposes. During a typical mission, the double filmstrip of FIG. 6 will be scanned from one of its center sections 31, 32 out to one end or the other as the mission is completed and ends with the simulator simulating an actual aircraft parked at the ramp.

In the general airport image" phase of the mission provided as the airport first comes into view, one of center sections 31, 32 is first'utilized. Which frame of section 31 or which frame of section 32 will first be scanned depends, of course, upon the simulated azimuth at the moment the range of the simulated aircraft is determined to be sufficiently within range to present a general airport image display and when the range of the simulated aircraft is within that predetermined range, the film drive is slewed to position the frame corresponding to that azimuth to be viewed by the scanner. Left Turn section 31 of the filmstrip and Right Turn" section 32 carry the same frames, but they are printed in reverse order. When a circling approach is to be made, successive azimuth frames of the filmstrip are scanned. The runway direction is assumed to correspond to azimuth insofar as the azimuths indicated adjacent the filmstrip in FIG. 6 are concerned. If the simulator simulates an actual aircraft which has turned left around the airport, the 0 azimuth frame at the end 33 of section 31 will be scanned as the simulator simulates an actual aircraft which comes within the approach window, and conversely, the 0 frame at end 34 of section 32 will be scanned if a right turn has been effected. In either case, when either frame 33 or frame 34 is reached, the actual aircraft would be in proper position, assuming its elevation is proper, to begin an approach and the simulator would be conditioned to receive the first frame of the approach film section. The pairs of approach, landing, taxi and park sections at opposite ends of the film may be the same, of course, but with succeeding frames running in opposite directions with respect to one another.

To provide a display during a simulated takeoff, the strip section containing the landing frames is employed and advanced in the same direction for takeoff as for landing, the section of filmstrip for either maneuver preferably covering a distance of travel (e.g., 10,000 feet) long enough to allow either maneuver. As the simulator simulates an actual aircraft which begins to lift and immediately after being completely airborne, the FSS scanning raster is distorted to simulate a visual change in altitude. As soon as the simulator simulates an actual aircraft which is airborne, and well-before the taxi" section of frames is reached, the film scanning system is disabled, and the entire image is generated by the background system of the type shown in the Ebeling-Paufve application. The approximate footage of 70 mm. film required for the various phases in an exemplary design of the invention is shown in FIG. 6. The 830 feet provided for a general airport image strip assumes that each frame of that section covers 6 are minutes of azimuth. An approach strip simulating an approach from 2 miles out with a new frame provided every l0 feet using the 25-picture matrices of FIG. 4 requires approximately 250 feet to 70 mm. film. Landing or takeoff from a 10,000 foot runway also requires about 250 feet. Taxiing and parking require about 120 feet and 50 feet respectively. The total 3,000 feet of film used for a direct approach with the type of turn preestablished may be carried on a spool approximately 16 inches in diameter.

During any phase of the simulated mission the required frame rate can vary from some maximum amount all the way down to zero. For example, the frame rate at which one of the general airport image section 31 or 32 advances will become zero if the simulator simulates an actual aircraft which approaches the airport at a fixed azimuth. For this reason, conventional stop-motion film transports using shutters are unsuitable, since intolerable flicker would be produced at low film advance rates, and a continuous projection film advance system is required, just as in the mentioned Hemstreet systems. A variety of continuous projection film advance systems are known in the cinematographic arts and need not be described in detail.

In FIG 11 the fields or areas covered by the rasters of television projectors l, 2 and 3 on screen S during a simulated zero bank angle condition are illustrated as rectangles 81, 82 and 83 respectively. If the simulator simulates an actual aircraft which is heading directly toward the simulated airport at a given pitch angle and zero bank angle shortly after the general airport image first comesinto view, the general airport image will be inset into the center of the field 82 of middle projector 2, perhaps as shown at 85a in FIG. 11. If the simula- 5 tor simulates an actual aircraft which instead were heading somewhat to the right of the airport at such a time, but at the same pitch angle and bank angle, the FSS video instead might be inset partially into the field of projector l, as indicated at 85b. If the simulator simulates an actual aircraft which was heading somewhat to the left of the airport, still at zero bank angle but at a steeper (nosedown) pitch angle, the video might be inset into the field of projector 3, for example, up higher in the field of projector 3 due to the steeper pitch angle, as shown at 85c in FIG. 11. If the simulator simulates an actual aircraft which instead were banked to the right and pitched upwardly but headed directly toward the airport, the inset video would be rotated and shifted downwardly, as depicted by rectangle 85d. During such a banked condition, the entire rasters of all three projectors are tilted or banked on screen S, as indicated by dashed rectangles 81', 82 and 83', so that the vertical scan direction of each line of the inset video remains parallel at all times to each vertical background scan line. Rotation of the rasters of all three projectors in accordance with simulated bank angle 9 is intended to be illustrated in FIGS. 2 and by a dashed line representing the physical rotation capability of the projector deflection coils. For certain heading conditions it will be apparent that portions of the image must be inset into two of the projector fields, as typified by rectangle 85b. As the simulator simulates an actual aircraft which flies nearer to the airport, the inset video will occupy larger and larger amounts of the screen. Rectangles 85a and 85f both represent the video inset when the actual aircraft being simulated is heading directly toward the airport at the same pitch angle and at zero bank angle, but rectangle 85f, being much larger than rectangle 8511, represents the video inset at a simulated range much closer to the simulated airport.

The deflection control system for the airport image FSS is illustrated in block form in FIG. 7. The sweep generators of the three projectors are shown all triggered simultaneously from the common timing or pulse source 19 which is formed of a 36 kc. oscillator and a l200-line counter. The 36 kc. oscillator being connected to trigger the three vertical sweep generators, and the output of a l200-Iine counter being connected to trigger the horizontal sweep generators at a 60 c.p.s. rate. The same timing source is used to trigger and synchronize the sweep generators of the background image generator 7 which are individually controlled from respective projector sweep generators-For simplicity of drawing, the outputs of the projector sweep generators 20 are not shown as being connected to the background image generator 7 in FIG. 7. However, such connections are necessary for proper operasweep generators of the three projectors are triggered simultaneously, the instantaneous sweep rates of the three vertical scans are generally not the same when a background is being provided by background image generator 7. The instantaneous vertical sweep rate in the background image generator 7 is varied in accordance with background elevation data in the manner disclosed in the mentioned EbeIing-Paufve application, as illustrated by the input signals on lines 7a, 7b and 70 to the three vertical sweep generators.

Because the instantaneous sweep rates of the three projectors all may and generally will differ, it will be seen to be necessary that video signals to be inset into the field of a given one of the three projectors be synchronized with the sweep signals of that particular projector. For that reason, the basic horizontal and vertical sweep signals associated with each given projector are used as the basic sweep signals for the flying spot scanner 21 while the photomultiplier 24 is generating video signals to be inset into the field of that respective projector.

tion of the system as illustrated in FIG. 2. While the vertical,

It will be seen from FIG. 11 that the particular scan line in any projector field when the projector should begin insetting a video signal from the image generator 8 and the particular scan when it should discontinue insetting video signals from the image generator 8 will depend upon the heading of the simulated aircraft relative to the line along which the picture being scanned was taken, and to the simulated range of the simulated aircraft from the simulated airport, as range will determine the size of the image being inset. To provide a scene of the type depicted in FIG. 11 by rectangle 85b, which lies halfway in field 81 of projector 1 and halfway in field 82 of projector 2, with all three projectors progressing simultaneously from left to right across their respective fields with successive upward vertical scans, it will be seen that video signals portraying the right half of the airport image 85b will be generated during the first several scans of a field and applied to projector 2, that no airport image video will be generated or inset into the background for some time while all three projectors scan the middle portions of their fields, and thenthat video signals portraying the left half of airport image 85!; will be generated during the last several scans of the field and will be applied to projector 1.

Throughout the general airport image phase, each projector receives background video signals from the background image generator 7 when it is not receiving FSS generated video from the airport image generator 8. Switching logic circuit 91, which determines at each instant during each field which projector (or projectors), if any, are to receive the FSS generated video from the airport image generator 8, and hence which set of projector waveforms should be used to derive the flying spot scanner sweep waveforms, is described in greater detail in connection with FIGS. 13 and 15. Because the projector fields are scanned regularly, repetitively and simultaneously, but the video signals which they are to display must be derived at different times during a given field, depending upon simulated heading and-range of the aircraft being simulated, it will be seen that switching logic circuit 91 must control the FSS scanning system of the airport image generator 8 so that the video required during a given field is both generated during the proper-scan lines of the field and routed to be displayed by the proper one of the three projectors. As shown in FIG. 7, outputs of the vertical and horizontal sweep generators of the projectors 1, 2' and 3 are connected to the switching logic circuit 91 which selects and delivers at an output thereof the vertical and horizontal sweep signals of one'of the projectors in accordance with the particular projector which is to display the inset image from image generator 8. In order to make this selection, range and heading signals are supplied to circuit 91 from the flight computer 17 by means ofa cable 26.

In FIG. 7 the output signals on lines 94, 95 from switching circuit 91 carry, during each projector scan line, the horizontal and vertical sweep waveforms H, and V, of the particular projector selected by switching circuit 91 to display the video signal resulting from a given vertical scan line of FSS 21. During the general airport image phase of a mission, the waveforms H, and V, are modified by distortion computer 96, which provides FSS raster distortion as a function of the difference between instantaneous aircraft elevation angle (relative to the airport) and the reference elevation angle at which the photograph then being scanned was taken. Various functions which determine the amount and type of distortion to be performed by computer 96 are supplied thereto from flight computer and control system 17 by means of a cable 27. If instantaneous aircraft position coincides with the reference elevation at which the transparency then being scanned was taken, distortion computer 96 does not modify the relative amplitudes of the H, and V, waveforms. If, however, the simulator elevation angle exceeds the transparency reference elevation angle, the vertical sweep amplitude of waveform V, is proportionally reduced, so that the vertical height of the FSS raster is reduced, with the result that the video signal derived during a given time interval of an FSS vertical scan will be spread out over a larger portion of the projector vertical scan which displays it, thereby stretching out the display video signal on the screen. When simulator elevation is less than the transparency reference elevation a converse adjustment occurs. Distortion computer 96 is described below in greater detail in connection with FIG. 14.

In addition, the various functions supplied to the distortion computer 96 from the flight computer 17 may dictate a distortion of the waveforms of signals H, and V, to simulate a change in heading.

The output waveforms H, and V,, from distortion computer 96 are applied to raster position computer 99, which also receives an input signal commensurate with simulated pitch angle, and from that input signal -controls the positioning of the FSS scanning raster relative to the picture being scanned, in order that the video signals produced by the FSS be properly synchronized with the sweep waveforms of the particular one of the three projectors selected at any instant to display the FSS video signal. During all phases of a mission, it will be appreciated that simulated nosedown pitching requires that the airport image be inset up higher in the window scene received by the students, and to provide that effect, raster position computer 99 moves the FSS raster upwardly and downwardly on the photograph being scanned as a function of simulated pitch angle. During the general airport image phase of a mission, changes in simulated heading affect switching circuit 91 to determine during which scan lines of a field a selected one (or two) of the projectors receive the generated video, and affect raster position computer 99 to approximately position the FSS raster relative to the picture being scanned, and hence determine the position of the image in a left-right sense in one (or two) of the projector fields. Changes in simulated bank angle do not cause rotation of the FSS raster relative to the photograph being scanned, and each scan line across the photograph remains vertical even though the simulated aircraft banks. Simulation of bank angle is preferably effected, as mentioned above, by tilting the tasters swept by pro jectors 1, 2 and 3 in accordance with simulated bank angle. During the approach phase of a mission when all of the FSS airport image video is inset into the field of central projector 2, simulated pitch angle changes continue to raise or lower the position of the video inset in the projector 2 field, bank angle changes continue to rotate the projector rasters, and changes in simulated heading continue both to determine which vertical scan lines of projector 2 carry which lines of video generated by the FSS and to horizontally position the FSS raster on the picture being scanned. A simplified form of raster position computer is described below in connection with FIG. 16. As shown in FIG. 16, raster position computer 99 may comprise a simple adder circuit 16A1 for adding a signal sin 6 commensurate with pitch angle to the vertical sweep waveform which has been selected by switching circuit 91 (FIG. 7) and distorted by distortion computer 96. As the simulator simulates an actual aircraft which pitches downwardly, the negative sin 0 quantity lowers the DC level of the vertical sweep waveform, thereby lowering the FSS raster on the picture being scanned and thereby raising the position of the inset video in the final display. Simulated pitching affects the position of the video in the same manner during all phases of the mission.

During the general airport image phase, the selected picture is scanned with a raster of 600 lines progressing from left to right by the three projectors. In order that the video to be generated and applied to one (or two) of the projectors during a given 600-line field be properly generated as it is switchably applied to one or two projectors, raster position computer 99 must approximately position the origin of the FSS raster to one (or two) locations relative to the selected picture during each 600-line field.

In FIG. 16 a signal on line 129 which varies in accordance with simulated heading and which is derived in a manner explained below in connection with FIG. 13, is applied to amplifier 16A2 to be added to the horizontal waveform H, from distortion computer 96. During the taxi phase a portion of the in greater detail.

Waveform H,, and V,, from raster position computer 99 are routed to a high bandwidth multiplier circuit 105, preferably comprising two diode quarter-squares" multipliers, for example, wherein each waveform is multiplied, during the general airport image phase, by a function of the instantaneous range R of the simulated aircraft from the airport, to vary the waveform amplitudes and hence the size of the FSS raster. As simulated range decreases, multiplier circuit 105 proportionally decreases the horizontal and vertical sweep amplitudes, thereby decreasing the size of the FSS raster, which results in an increase in the size of the general airport image in the final display. During the approach phase, changes in range are preferably simulated by substitution of successive film frames each taken closer to the airport, and hence it is unnecessary for multiplier system 105 to vary the sweep amplitudes during that phase. However, in some embodiments of the invention it may be desirable to utilize multiplier 105 to vary the sweep amplitudes during this phase, which will allow the use of fewer film frames taken greater distances apart. The control of multiplier system 105 will be seen to provide an effect similar to that which a zoom" lens provides on a projected picture.

The output waveforms H, and V on lines 107 and 108 are applied to adder circuits 113 and 114 to be added to respective F and Fy signals representing the coordinates on the frame or matrix then in front of the FSS, of the center of the particular one picture to be scanned. Thus, The F and Fy signals position the FSS raster relative to a SO-picture frame during the general airport image phase so as to scan the appropriate one of the 50 pictures, and to approximately center the origin of the FSS sweep system at the center of the selected picture. During the approach phase, the F and Fy signals position the FSS raster relative to one picture of a 25- picture film frame, and during the taxi phase relative to one strip of five panoramic filmstrips contained in a film frame. The F and F signals may be derived from simple decoder circuits in a manner to be described in connection with FIG. 12.

The output signals H and V,, on lines 115 and 116 are applied to conventional driver amplifier circuits shown at 118 and the output signals from driver circuits 118 drive the deflection yoke 120 of the FSS. Because optimum focus depends upon instantaneous deflection, a known form of focus computer 122 is preferably provided to receive deflection signals H, and V, and to provide compensating variations in the current in focus coil 124, thereby to provide uniform spot focusing over the entire FSS scanning raster. The FSS raster may extend over more than one picture of a matrix, but the video signals from only one picture at a time should be inset, and accordingly it becomes necessary to blank out the FSS when the FSS spot reaches the edges of the particular picture being scanned. Unblanking circuit 125 receives the H, and V sweep waveforms and the F and F signal, and blanks out the FSS during those times when the FSS beam would extend vertically or horizontally outside the edges of the particular picture being scanned. The unblanking circuit may comprise a plurality of simple comparator circuits (not shown), one of which blanks out the FSS whenever the instantaneous value of the V,, waveform exceeds (F k), and another of which blanks out the FSS when the instantaneous value of the V waveform becomes less than (F k), where kis'a constant equal to one-half of theheight of the picture being scanned.

Different values of k representing difi erent, picture heights are applied to the comparators during the three different phases of operation, by contacts (not shown) of switching circuits (P1, P2, P3) described below. A further pair of similar comparators (not shown) responsive to the H,, waveform, the F voltage signal, and a further constant k, similarly blank out the FSS when H,, becomes greater than (F -l-k) or less than (F,,-ka:), where k is-a constant equal to one-half of the picture width.

Thus, it will be seen that generation of the general airport image requires (l) that the film drive slew the filmstrip in accordance with the bearing of the aircraft being simulated to position a given SO-picture frame of the 70 mm. filmstrip in front of the FSS, (2) that an elevation decoder circuit receive an input commensurate with the elevation angle of the aircraft being simulated relative to the airport and provide proper F and F positioning signals to center the origin of the FSS scanning system over the proper one of the pictures, (3) that the multiplier circuit 105 control the FSS raster size in proportion to simulated range R from the airport, (4) that the raster position computer 99 appropriately shift the FSS raster to locate the airport image in the proper vertical position relative to the projector fields, and hence relative to the simulator cockpit windows, (5) that the distortion computer appropriately distort the FSS raster in accordance with the difference between the instantaneous elevation angle of the simulated aircraft and the reference elevation angle from which the picture being scanned was taken, and (6) that switching circuit 91 select for each vertical scan of the FSS the basic sweep waveforms from the particular projector upon which the FSS video resulting from that scan is to'be displayed, and route the generated video to the appropriate one of the projectors. v j

The operation of the system of FIG. 7 perhaps maybe better understood by considering the derivation of the FSS sweep waveforms in the reverse order from that shown. in FIG. 7. The F and F signals select a particular picture by approximately centering the FSS raster relative to one picture. The multiplier 105 determines the size of the FSS raster. Position computer 99 shifts the raster up or down relative to the selected picture, and distortion computer slightly distorts the shape of the FSS raster to simulate changes in perspective. Switching logic circuit 91 determines which projector is to display the video generated during a given vertical scan.

The operation of the FSS scanner deflection system of FIG. 7 during the approach phase (i.e., final approach, touchdown and roll along the main runway) is very similar to the operation described above in connection with the general airport image phase, with some differences which now will be discussed. As the simulator simulates an actual aircraft which flies down the glideslope, or more precisely, within the glideslope envelope, successive frames of the approach film are presented to the FSS at a rate corresponding to the component of simulated aircraft velocity along the glideslope. Because the pictures on successive frames of the approach filmstrip were taken at small distance increments down the glideslope, it becomes unnecessary to decrease FSS raster size as a function of range to enlarge the image in the projected display, as is done in the case of the general airport image, an accordingly, the range R input signal to multiplier may be replaced by a fixed potential k,. If it is desired, however, in certain simulation applications, to simulate an approach with a fewer number of frames taken a greater distance apart, the transition from one frame to the succeeding adjacent frame may be smoothed or interpolated by applying slight sawtoothlike input signals to multiplier circuit, 105, to slightly gradually decrease the FSS raster size as each picture is scanned by the FSS and then reset the multiplier range input signal to a reference level as a new picture is presented to the FSS.

' Also, while the input signal to multiplier 105 frequently will beheld constant as the simulator simulates an actual aircraft which descends along the glideslope because successive frames along the approach strip were taken the same distance apart, it sometimes becomes desirable to use different frame spacings during different portions of the approach phase, in order that. the photographs used may be taken different distances apart. In such cases, for example, one fixed input k, may be applied to multiplier 105 during one portion of the ap 

1. Visual display apparatus for providing a display of an area to an operator of a vehicle simulator, comprising (1) means responsive to controls of said simulator for providing a plurality of computed quantities; (2) a plurality of picTures of said area each representing a view of said area from the same distance from a reference point associated with said area but each a view from a position having a different angular orientation from said reference point; (3) control means responsive to said computed quantities for selecting at a given instant a single one of said pictures in accordance with the instantaneous simulated azimuth and elevation angles of a simulated vehicle relative to a simulated reference point; (4) projection means for projecting an image of the selected one of said pictures to be viewed by said operator; and (5) means responsive to said computed quantities for varying the size of the projected image inversely in accordance with the instantaneous simulated distance of said simulated vehicle from said simulated reference point.
 2. Visual display apparatus as defined in claim 1 including means responsive to said computed quantities for distorting said projected image in accordance with the difference between the angular orientation of said selected one of said pictures and one of said simulated angles.
 3. Visual display apparatus as defined in claim 1 in which said projection means includes scanning means for viewing said selected one of said pictures, in which said plurality of pictures are arranged in groups, each of said groups comprising pictures all taken from the same azimuth angle from said reference point at different elevation angles from said reference point, and in which said control means is operative to position a selected group of said pictures relative to said scanning means in accordance with the instantaneous simulated azimuth of said simulated vehicle and operative to control said scanning means to view said selected one of said pictures from said selected group in accordance with the instantaneous simulated elevation angle of said simulated vehicle.
 4. Visual display apparatus as defined in claim 1 in which said plurality of pictures comprises a strip of transparent film having a plurality of successive frames, each of said frames comprising rows and columns of said pictures, each of the pictures of a given frame representing a view of said area from a common one of said angles from said reference point.
 5. Visual display apparatus as defined in claim 1 in which said projection means includes means for projecting a background scene to be viewed by said operator and in which said projection means is operative to inset said projected replica into said background scene.
 6. Visual display apparatus as defined in claim 5 in which said projection means includes further means responsive to at least one of said computed quantities commensurate with a simulated attitude angle of said simulated vehicle for controlling the position at which said projected image is inset into said background scene.
 7. Visual display apparatus as defined in claim 5 in which said projection means comprises further means for translating said projected image to a position within said background scene in accordance with simulated pitch angle of said simulated vehicle.
 8. Visual display apparatus as defined in claim 5 in which said projection means comprises further means for angularly rotating said projected image to a position within said background scene in accordance with simulated bank angle of said simulated vehicle.
 9. Visual display apparatus as defined in claim 1 in which said projection means comprises flying spot scanner means for scanning the selected one of said pictures with a controlled pattern to derive video signals, and television projector means responsive to said video signals for projecting said image to be viewed by said operator.
 10. Visual display apparatus as defined in claim 9 in which said means for varying the size of said projected image comprises means for controlling the scanning pattern of said flying spot scanner means.
 11. Visual display apparatus as defined in claim 9 in which said television projector means comprises a pluRality of television projectors each having first and second sweep circuits and each having an intensity control means, and in which said apparatus includes means responsive to one of said computed quantities commensurate with a simulated attitude angle of said simulated vehicle for selectively applying signals from the sweep circuits of one of said television projectors to control said scanning pattern of said flying spot scanner and for selectively applying said video signals to the intensity control means of said one of said television projectors.
 12. Visual display apparatus as defined in claim 9 in which said television projector means includes raster scanning means, said apparatus further including means for angularly rotating said raster scanning means in accordance with an attitude angle of said simulated vehicle.
 13. Visual display apparatus as defined in claim 1 in which said projection means includes a first flying spot scanner means for deriving a first video signal representing a background scene; a second flying spot scanner means for scanning the selected one of said pictures; and television projector means responsive to said first and second video signals for projecting a background scene with said image inset into said background scene.
 14. Visual display apparatus as defined in claim 13 in which said television projector means includes a plurality of television projectors, and in which said first flying spot scanner means includes delay means for applying respective portions of said first video signal repeatedly to respective one of said television projectors.
 15. Visual display apparatus for providing a display of an area to an operator of a vehicle simulator, comprising (1) means responsive to controls of said simulator for providing a plurality of computed quantities; (2) a plurality of groups of pictures of said area, each picture of a given group representing a view of said area from the same distance away from a reference point associated with said area, each different group of pictures representing views of said area from positions at different respective distances from said reference point, and each picture of a given group representing a view from a position having a different angular orientation from said reference point than other pictures of the same group; (3) control means responsive to certain of said computed quantities for selecting at a given instant a single one of said pictures in accordance with the instantaneous simulated azimuth and elevation angles of a simulated vehicle relative to a simulated reference point; (4) first flying spot scanner means for deriving a first video signal representing a background scene; (5) second flying spot scanner means for scanning the selected one of said pictures to provide a second video signal; (6) and projection means responsive to said first and second video signals for providing a background scene with an image of said pictures inset into said background scene.
 16. Visual display apparatus as defined in claim 15 in which each picture of a given group represents a view having a different combination of azimuth and elevation angles than other pictures of the same group, a first plurality of sets of said pictures representing views having the same respective azimuth angle from said reference point, and a second plurality of sets of said pictures representing views having the same respective elevation angle from said reference point.
 17. Visual display apparatus as defined in claim 15 in which said plurality of groups of pictures comprises a transparent filmstrip having successive frames, each of said frames comprising one of said groups of said pictures.
 18. Visual display apparatus as defined in claim 15 including means responsive to computed quantities commensurate with simulated deviation of said simulated vehicle from a simulated reference line for varying the operation of said flying spot scanner means to vary the apparent perspective of said imaGe inset into said background scene.
 19. Visual display apparatus as defined in claim 15 in which said projection means includes means responsive to a further of said computed quantities commensurate with a simulated attitude angle of said simulated vehicle for controlling the position at which said projected image is inset into said background scene.
 20. Visual display apparatus as defined in claim 15 in which said projection means comprises a raster scanning television projector means, and in which said apparatus includes means for angularly rotating the raster of said television projector means in accordance with an attitude angle of said simulated vehicle.
 21. Visual display apparatus for providing a display of an area to an operator of a vehicle simulator, comprising (1) means responsive to controls of said simulator for providing a plurality of computed quantities; (2) a plurality of groups of pictures of said area, the pictures of a given group representing views of said area from positions the same distance away from a reference point associated with said area at different respective azimuth angles from said reference point and all at the same elevation angle from said reference point; (3) control means responsive to certain of said computed quantities for selecting at a given instant a single one of said pictures in accordance with the simulated distance and azimuth angle of said simulated vehicle from a simulated reference point; (4) flying spot scanner means for scanning a selected portion of said selected one of said pictures to derive a video signal; (5) television projector means responsive to said video signal for projecting an image of said selected portion of said selected one of said pictures; and (6) means controlled in accordance with the simulated heading of said simulated vehicle for controlling said flying spot scanner means to select the portion of said selected one of said pictures being scanned by said scanner means.
 22. Visual display apparatus as defined in claim 21 further comprising means responsive to the azimuthal position of said simulated vehicle from said simulated reference point for varying the scanning pattern of said scanner means on said selected one of said pictures to vary the perspective of said display.
 23. Visual display apparatus for providing a display of an area to an operator of a vehicle simulator, comprising (1) means responsive to controls of said simulator for providing a plurality of computed quantities; (2) a motion-picture filmstrip having a plurality of successive sections, each section comprising a plurality of successive frames, each successive frame comprising a plurality of pictures of said area; (3) flying spot scanner means for scanning selected successive portions of said successive frames to provide video signals; (4) television projector means responsive to said video signals for providing a display to be viewed by said operator; (5) film-feed means responsive to certain of said computed quantities for positioning successive sections of said filmstrip before said flying spot scanner means and for positioning successive frames of said filmstrip sections before said flying spot scanner; and (6) means responsive to certain of said computed quantities for controlling said flying spot scanner to scan a single one of the plurality of pictures of a frame positioned before said scanner at a given instant.
 24. Visual display apparatus as defined in claim 23 in which all of the frames of one of said sections of said filmstrip represent views of said area from positions which are equidistant from a reference point associated with said area.
 25. Visual display apparatus as defined in claim 23 further comprising means for deriving further video signals representing a background area, and means for applying said further video signals to said television projector means.
 26. Visual display apparatus as defined in claim 23 in which said fiLmstrip includes successive indicia coded adjacent various of said frames along the length of said filmstrip, in which said apparatus includes means for sensing said indicia to provide a first signal, in which said film feed comprises servomechanism means responsive to a computed quantity commensurate with simulated distance of said simulated vehicle from a reference point associated with said area and responsive to said first signal.
 27. Visual display apparatus for providing a composite display of an area to an operator of a vehicle simulator, comprising (1) means responsive to controls of said simulator for providing a plurality of computed quantities; (2) a plurality of television projectors, each of said projectors having sweep generator means and the projectors being arranged to provide respective adjacent portions of the composite display; (3) flying spot scanner means for scanning a picture to provide a video signal representing a picture replica to be inset into the display; (4) first switching means for selectively connecting signals at different times from different ones of said sweep generator means to control said flying spot scanner means; (5) second switching means for selectively applying said video signal at different times to different ones of said television projectors; and (6) means responsive to certain of said computed quantities for controlling the operation of said switching means.
 28. Visual display apparatus as defined in claim 27 wherein the sweep generator means of said projectors are connected to be triggered in synchronism with each other; said apparatus including counter means for counting successive scan lines of said projectors; and wherein said means for controlling said switching means comprises means for computing a first quantity commensurate with the line width of the picture replica to be inset into the composite display, means for computing a second quantity commensurate with the desired location of a reference portion of said picture replica within said composite display, means for combining said first and second quantities to provide line-starting and line-stopping quantities for each of said projectors; and comparator means for comparing said line-starting and line-stopping quantities with the count in said counter means to selectively operate said switching means.
 29. Visual display apparatus as defined in claim 27 wherein said means for computing said first quantity is responsive to a computed quantity commensurate with simulated distance of said simulated vehicle from a reference point associated with said area.
 30. Visual display apparatus as defined in claim 27 wherein said means for computing said second quantity is responsive to a computed quantity commensurate with simulated heading of said simulated vehicle.
 31. A method of simulating from a pair of objects the appearance of an area as viewed from one of a plurality of selected viewpoints, which objects each have the appearance of said area as viewed from a respective reference viewpoint, with the range of each reference viewpoint from said area being approximately equal to one another and each reference viewpoint having a different angular orientation with respect to said area, comprising the steps of selecting one of said objects in accordance with the angular orientation of one selected viewpoint with respect to said area, projecting an image of the selected object onto a viewing surface, and distorting said image in accordance with the difference between the angular orientation of said one selected viewpoint and the angular orientation of the appearance of said area on said selected object with respect to said area.
 32. A method of simulating the appearance of an area as defined in claim 31 further comprising the step of distorting said image in accordance with the difference between the range of said one selected viewpoint from said area and the range of the reference viewpoint of said selected object from said area.
 33. Apparatus for simulating from a pair of objects the appearance of an area as viewed from one of a plurality of selected viewpoints, which objects each have the appearance of said area as viewed from a reference viewpoint, with the range of each reference viewpoint being approximately equal to one another and each reference viewpoint having a different angular orientation with respect to said area, comprising means for selecting one of said objects in accordance with the angular orientation of one selected viewpoint with respect to said area, means for projecting an image of the selected object onto a viewing surface, and means for distorting said image in accordance with the difference between the angular orientation of said one selected viewpoint and the angular orientation of the appearance of said area of said selected object with respect to said area.
 34. Apparatus as defined in claim 33 further comprising means for distorting said image in accordance with the difference between the range of said one selected viewpoint from said area and the range of the reference viewpoint of said selected object from said area.
 35. Visual display apparatus for providing a display of an area to an operator of a vehicle simulator, comprising means responsive to controls of said simulator for providing the plurality of computed quantities; a plurality of pictures of said area each representing a view of said area from the same distance from a reference point associated with said area, but each a view from a position having a different angular orientation from said reference point; control means responsive to certain of said computed quantities for selecting at a given instant a single one of said pictures in accordance with the instantaneous simulated azimuth and elevation angles of a simulated vehicle relative to a simulated reference point; and projection means for projecting an image of the selected one of said pictures to be viewed by said operator.
 36. Visual display apparatus as defined in claim 35, further comprising means for altering the apparent prospective of the projected image of the selected one of said pictures in accordance with the difference between the simulated angular orientation of said simulated vehicle from said simulated reference point and the angular orientation of the projected image of the selected one of said pictures with respect to said reference point.
 37. Visual display apparatus as defined in the claim 36 further comprising a means responsive to a further one of said computed quantities for varying the size of the projected image inversely in accordance with the instantaneous simulated distance of said simulated vehicle from said simulated reference point.
 38. Visual display apparatus as defined in claim 35 wherein said projection means includes a plurality of television projectors, each of said projectors having sweep generator means and the projectors being arranged to provide respective adjacent portions of the display, and flying spot scanner means for scanning the selected one of said pictures to provide a video signal representing a picture replica to be inset into the display; said apparatus further comprising first switching means for selectively connecting signals at different times from different ones of said sweep generator means to control said flying spot scanner means; second switching means for selectively applying said video signal at different times to different ones of said television projectors; and means responsive to certain of said computed quantities for controlling the operation of said switching means.
 39. Visual display apparatus as defined in claim 38 in which the sweep generator means of said projectors are connected to be triggered in synchronism with each other; said apparatus including counter means for counting successive scan lines of said projectors; and wherein said means for controlling said switching means comprises means for computing a first quantity commensurate with the line width of the picturE replica to be inset into the display, means for computing a second quantity commensurate with the desired location of a reference portion of said picture replica within said display, means for combining said first and second quantities to provide line-starting and line-stopping quantities for each of said projectors, and comparator means for comparing said line-starting and line-stopping quantities with the count in said counter means to selectively operate said switching means.
 40. Visual display apparatus as defined in claim 38 wherein said means for computing said first quantity is responsive to a computed quantity commensurate with simulated distance of said simulated vehicle from a reference point associated with said area.
 41. Visual display apparatus as defined in claim 38 wherein said means for computing said second quantity is responsive to a computed quantity commensurate with a simulated heading of said simulated vehicle.
 42. A visual display apparatus as defined in claim 35 wherein said projection means includes means for scanning the selected one of said pictures, means for sensing the scanning position of said scanning means and generating positional signals corresponding thereto, means for generating sweep signals for said scanning means, and means for sensing the difference between said sweep signals and said positional signals and being coupled to said sweep generating means to correct the position of said scanning means with respect to the selected picture.
 43. In a visual display apparatus for providing a display of an area by projecting an image from a filmstrip to the operator of a vehicle simulator, the improvement comprising a filmstrip having a plurality of pictures of said area each representing a view of said area from the same distance from a reference point associated with said area but each a view from a position having a different angular orientation from said reference point, and means responsive to the operation of controls of said simulator by the operator for selecting any one of said pictures and for projection of an image thereof to the operator.
 44. A visual display apparatus as defined in claim 43 wherein said means selects a single one of said pictures in accordance with the instantaneous simulated azimuth and elevation angles of a simulated vehicle relative to a simulated reference point.
 45. In a visual display apparatus for providing a display of an area by projecting an image from a filmstrip to the operator of a vehicle simulator, the improvement comprising a plurality of groups of pictures of said area, each picture of a given group representing a view of said area from the same distance away from a reference point associated with said area, each different group of pictures representing views of said area from positions at different respective distances from said reference point, and each picture of a given group representing a view from a position having a different angular orientation from said reference point than other pictures of the same group, and means responsive to the operation of controls of said simulator by the operator selecting any one of said pictures and for projection of an image thereof to the operator.
 46. A visual display apparatus as defined in claim 45 wherein said means selects a single one of said pictures in accordance with the instantaneous simulated azimuth and elevation angles of a simulated vehicle relative to a simulated reference point. 